Even New Birth Control Pills May Raise Women's Breast Cancer Risk

Use of oral contraceptives may increase risk of breast cancer, although the overall absolute increase was relatively small, according to a study from Denmark.

A new study is showing the link between the use of birth control to increased risk of breast cancer.

The new study was published December 7 in the New England Journal of Medicine. Women who used any form hormonal contraception for more than 10 years (1.38, 95% CI 1.26-1.51) had a higher risk compared to those who reported less than 1 year of use (1.09, 95% CI 0.96-1.23)(P=0.002), they wrote online in the New England Journal of Medicine.

For some perspective, about 252,710 American women were diagnosed with breast cancer in 2017, according to estimates from the National Institutes of Health; 12.4 percent of women will hear the diagnosis at some point in their lives.

"The increased risk also with newer progestins in hormonal contraceptives has not been shown consistently before, though progestins in postmenopausal therapy has also been found to increase the risk of breast cancer", she added.

Beyond the fact that they provide an effective means of contraception and may benefit women with menstrual cramping or abnormal menstrual bleeding, "the use of oral contraceptives is associated with substantial reductions in the risks of ovarian, endometrial, and colorectal cancers later in life".

The longer women used hormonal contraception, the greater their risk of breast cancer, the researchers found. Most cases of breast cancer were seen in women using oral contraceptives in their 40s.

"I don't think anyone's going to say stop taking oral contraceptives. That's not necessary and not supported by the data", said Dr. Roshni Rao, chief of breast surgery at New York - Presbyterian/Columbia University Medical Center in New York City, who was not involved with the study.

The study of nearly 2 million women in Denmark looked at women using birth control methods such as the pill, NuvaRing, or implants.

The data for the study was collected from 1.8 million Danish women for more than a decade.

The 20 percent increase in breast cancer risk varied by age and how long the women used hormone-based contraceptives, including pills, contraceptive patches, vaginal rings, progestin-only implants, and injections. However, using hormonal contraception for 10 years was linked with a 40 percent increase in the risk of breast cancer, compared with those who had never used hormonal contraception.

"Another thing that has not been clear before is that after discontinuation, if you have used this product for more than 5 years, the risk seems to be increased, even after 5 years of discontinuation of the drugs", chief author Dr. Lina Morch, a senior researcher at Copenhagen University Hospital told Reuters Health by phone.

"In the 1980s and 1990s, there was some optimism regarding the development of a formulation that would reduce a woman's risk of breast cancer", he said in the commentary, "but research into this possibility appears to have stalled". "Contraception itself is a benefit, of course, but this study indicates it might be worth considering an alternative to hormone contraception, like the copper intrauterine device or barrier methods like condoms". But if they had taken hormonal contraception for more than five years, the higher risk of breast cancer persisted for at least five years after their discontinuation of hormonal birth control, the study found.